


Weak

by silverryu25



Category: Undertale (Video Game)
Genre: Fluff, Inspired by another Story, Just a little bit of Angst, M/M, Mpreg, Red is falling, Skeleton Pregnancy (Undertale), but he's not there yet
Language: English
Status: Completed
Published: 2020-10-11
Updated: 2020-10-11
Packaged: 2021-03-08 02:47:17
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,341
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26958298
Author URL: https://archiveofourown.org/users/silverryu25/pseuds/silverryu25
Summary: Red really had enough.He was so close to getting some permanent peace, for better or worse, when his life was flipped upside down. Now he had three souls to care for and no idea if he could do it.He was fucked.
Relationships: future sanscest, no ship in this
Comments: 14
Kudos: 34





	Weak

**Author's Note:**

  * For [AssassinPyro13](https://archiveofourown.org/users/AssassinPyro13/gifts).
  * Inspired by [The Letter Z](https://archiveofourown.org/works/10233170) by [AssassinPyro13](https://archiveofourown.org/users/AssassinPyro13/pseuds/AssassinPyro13). 



> Zans is the Sans from an alternate UT universe in The Letter Z fic. AssassinPyro13 was nice enough to open the AU for use for anyone and then made some [adorable art you can see here](https://twitter.com/DayzLost4/status/1314865169827278852) with Zans and Red and since I am so freaking weak to any UT and UF Sans ship… here we are :D
> 
> Zans is 8 months pregnant in this fic, that would be around [chapter 16](https://archiveofourown.org/works/10233170/chapters/26689683) for those who have read it. If you haven’t and are into the theme of the fic (read the tags!) I highly recommend it X3
> 
> Red is a bara version in this fic >;3

The house was dark and silent, it had been like that the whole day. The windows being completely barred up made it impossible for the little light the outside offered to leak in, making it feel abandoned, empty, even though it was anything but.

The heavy silence was broken by a frustrated growl and the sound of many locks clicking into place.

The big skeleton that had broken the oppressive peace released a sigh as he leaned his head on the door, sockets closed and brows furrowed. He had fucking enough of dealing with this miserable place. Every day was a fight for survival, and every day it was harder and harder to try. He was nearing his limit, slowly thinking that giving up would be so much easier. It probably wouldn’t hurt much to finally end it given his HP. One good intent-filled hit and he’d be free…

With a shake of his skull and a growl to clear those dark thoughts, he turned away from the door. He didn’t have the luxury of letting himself think like that. Not now. Not anymore. Maybe while he had been alone, while he didn’t have… them to think about.

His brother had left to live in the capital a while ago. Being the captain of the guard made it impossible for him to stay in a remote place like Snowdin. So he left. And Sans stayed. His pride wouldn’t let him go with his brother. He didn’t want to be his weakness. Didn’t want to be a burden more than he had until now. So he stayed. And tried to make himself stay alive for his brother, for the rare times his brother would come to visit.

He would have probably given up a long time ago if he hadn’t promised his brother that he would stay alive.

That wasn’t one of his brightest moments. He knew that making promises would come to bite him in the coccyx, it always did, but Papyrus didn’t give him the option to say no.

So he promised. And he survived.

And now? Now he had three more reasons to stay alive. He was a real idiot.

With another sigh, he schooled his expression into his usual scowl, grabbed the bag of Grillby’s firmer, and went upstairs to his brother’s old room. He hoped he would not find dust there today. As he hoped every day. Something he thought he wouldn’t have to worry about since Papyrus moved out.

He paused at the door to the room, taking in all the warning signs and tape his brother had put up. It made his teeth rise in a fond smile as he let himself live in the moment for a little bit longer. A moment where there was nothing frightening about opening the door. Just fond memories of his brother and the times he spent reading him those stories he loved as a babybone.

Finally, gritting his teeth, he opened the door and zeroed in on the bed. Eyelights trembling a little.

With a soft sigh, relief flooding his soul, he walked up to the bed, not letting his sockets stray from the monster sleeping on top of it. The little monster was curled up on his side, obviously suffering some discomfort, which wasn’t surprising.

His belly was huge and heavily pregnant, making it impossible for the tiny skeleton to sleep on his back or belly. But that was probably only a part of it. Another was the collar around his neck. Red tried to remove it but it was impossible with the tools he had on hand and it rejected any kind of magic. Not surprising since it was a magic suppressing collar. Not being able to do much, Red had left it as is for now, until he can figure out how to snatch some equipment from the labs without Alphys noticing.

But the worst part was the uneasy sleep that seemed to be the small monster’s standard. It was like he hadn’t slept properly in forever.

Zans. Another Sans. Another him.

It had been around a month since Red, a nickname Zans gave him, had found the little monster. It hadn’t been a happy meeting.

Red was at his post, passing the time by drinking mustard and trying to stay awake so he wouldn’t be dusted as he napped. It was a boring as fuck day and he was tempted to leave early again. Not like anyone would notice with Boss gone. And if he left early he’d have more time to get wasted at Grillbz’. His main pastime recently.

Before he could make up his mind there was a loud crack, as if something exploded, and a rush of electrified air rushed over him.

“fuck!” He cursed as he stood up, preparing for an attack.

Whoever had enough magic to cause such a big explosion couldn’t be good news. Red prepared his magic, summoning a few sharpened bones and ready to either port away or summon a blaster, whichever proved to be a better option, and waited for whoever caused this.

And waited.

And waited.

… waited?

As moments passed and there was no sound, Red let the bones dissipate. Maybe whoever had made the explosion was dusted during it? Or if it was a fight maybe it was over and they ran off? 

“fuckin’ hell.” With a curse at his bad luck and an annoyed growl, he decided to go and check the place where the explosion came from. It would be bad to leave it and risk something or someone sneaking up on him later. And hell, at least it was something to do.

Cautiously, not making a sound in the snow despite his large frame, Red neared the offending spot. He didn’t have any bones summoned so the glow wouldn’t give him away, and his eyelights were dim. If there was anything dangerous there he would make sure to have the advantage of surprise.

As he closed in he could feel a little of the residual heat. It was a pretty big explosion to make the air that heated up in Snowdin forest, but he wouldn’t let that stop him. He could always port out if things got too  _ heated _ up.

Peeking from behind an especially wide tree that could hide his frame, Red glared at the centre of the crater the explosion had left. It wasn’t that deep, but it melted quite a bit of snow around the centre. And the centre wasn’t empty. There was something small in the middle.

It was hard to tell what it was in the forest’s gloom, but it didn’t look like it was moving. With a silent curse, Red decided to take that last step and see what it was. His magic was keyed up and ready to pull him out in a second if things went south.

Squelching his way through the melted muck, he cautiously neared the centre. As he got closer he started to realize it was a monster, and not just any monster, a skeleton monster. They were curled up on their side, wrapped around their swollen middle…  _ naked  _ swollen middle.

Red’s sockets snapped open at the sight, eyelights gone. What the hell? What was a  _ pregnant skeleton _ monster doing in the middle of the forest? And why the fucking hell were they half-naked? Was this a trap?

Spinning around, empty sockets glaring death all around, he tried to see if anyone was sneaking up on him. But after a few minutes of looking and listening there was nothing. No other monster. No trap. Nothing. Just the little pregnant skeleton in the middle of a crater.

“ain’t dis a real clusterfuck.” He whispered out and glared back at the monster curled up at his feet.

What was he supposed to do now? A pregnant monster wouldn’t survive long in this place, hell they wouldn’t survive five minutes in town. They didn’t look like they’d survive long enough to wake up honestly. It’s been a while since the explosion and the monster wasn’t showing any sign of moving.

Browbones furrowed, Red thought hard about his options. Taking the monster into town wouldn’t do any good, they were free walking EXP and someone would be more than happy to take it. Taking him to Papyrus would maybe give them a fighting chance, but Red wouldn’t risk putting his brother in danger. Not anymore. Finding the monster’s mate, if they had one, would be impossible since they weren’t from Snowedin and Red had no clue where to even start looking. Not to mention that he would be putting himself at risk by taking care of the monster while he searched.

Steeling his soul, Red summoned a sharpened bone. It was better to just put the monster out of their misery. Prolonging their suffering would help no one and at least Red could make sure it was fast and painless. Dying in their sleep would be merciful in this place.

Raising his hand high for a powerful strike, Red silently apologized to the monster as his hand started to descend. Just before he struck, the monster stirred and breathed out a name.

“papyrus.” Red barely caught it, but it made him freeze in place, the bone almost touching the skeleton’s ribs, right above their soul.

_ ‘papyrus?!’ _ Red incredulously thought. Did this monster know his brother? Were they Papyrus’ mate?!! How the fuck didn’t Red know about them?

Quickly dismissing the bone, not wanting to hurt the monster before he knew more, he ran a check over them.

**SANS 1 ATK 1 DEF**

*** He’s cold.**

The information he saw made the marrow in his bones freeze.  _ Sans _ . What the fucking unmerciful hell was this now?

Shaking off the shock, he knelt by the monster and gently put his hand on his chin, turning his head so he could see it. What stared back at him was a replica of his own face, without the scar and sharp teeth. But the shape of the skull, those bags under his sockets, it was the exact same. A face he glared at every morning in the mirror was staring at him in the middle of the forest.

His mind raced over possible explanations. He knew about the multiverse theory, but he couldn’t come up with a reason why this version of him was here. But one thing he did know, he couldn’t dust him. Not before he figured out how the monster came here and why.

“yer one unlucky bastard ta fall into my universe, ain’tcha?” He whispered out as he gently wrapped his arms around his small alternate.

And he was really small, barely half Red’s size. Even with the belly, Red could barely feel the small monster as he lifted him up. He hoped the monster wasn’t malnourished, food was pretty scarce here.

That was how he met Zans.

He had brought him home and warmed him up. Hours later, when Zans woke up, he questioned him about how he ended up here. But the small monster couldn’t remember much. His memory was spotty. The only thing he remembered was his brother and friends, and that he was trying to run from something or someone. But he couldn’t really remember how he ended up pregnant, just that thinking about it made him feel both happy and terrified.

Red didn’t press too much cause the smaller him looked like he was on the verge of a panic attack the more he thought about the pregnancy and where he came from. And there wasn’t much point. If he didn’t know how he got here, he couldn’t go back. So they decided to wait and see if his memory comes back.

In the meantime, Red offered him Papyrus’ old room and tried to make sure no one knew about Zans. Red couldn’t stay with the small monster the whole day and bringing him to the station with him was out of the question. Sans was too heavily pregnant to stay outside that long and had no magic to protect himself. So he stayed home, hidden. Alone.

Red could see it was starting to take a toll on the small monster, but there wasn’t much he could do about it. Not until he could move around better. And Zans was probably close to the end of his pregnancy, they just had to wait until then. Hopefully, it will be soon.

Reluctantly, Red put his hand on Zans’ shoulder and shook him awake. He didn’t want to wake the exhausted monster up, but Zans needed to eat. Both for himself and the two soulings he was carrying. Red was still shocked about the twins. He hadn’t heard of twins in forever, the underground was just too dangerous for something like that, and the magic involved in creating life was barely able to create one souling most times.

But here was Zans, with two bright specks in his clouded belly. The sight made Red’s soul react in a way he didn’t recognize. So he ignored it and just focused on providing enough food for all three souls.

Zans slowly stirred awake, sockets blinking unevenly. The little monster looked tired no matter how much he slept. It was mostly due to the pregnancy draining his magic, but part of it was the way his expression permanently looked sad, no matter his mood. Red tried to cheer him up a few times with bad jokes and even worse puns, but nothing helped. It was as if Zans’ face was stuck in a sad expression, no matter how he felt.

“huh?” A soft question made Red focus back on the moment. Zans was looking at him with bleary sockets, clearly still half asleep.

“here.” Red said as he showed the bag of food in Zans’ hands, helping him sit up with the other hand. 

The little monster blinked at the bag, opening it up. The moment he smelled the food Red could see him starting to drool a bit. He couldn’t blame him, it had been hours since Red left for work and sleep could do only so much to push the hunger down.

Zans dug into the food like a starving animal as Red watched amusedly. It was good that his appetite was this strong, cause Red didn’t want to force him to eat. Or do something more extreme, like take him to Alphys for a magic drip. He wanted to avoid any contact with that crazy lizard for as long as possible.

Practically inhaling the food, Zans finished it in moments, making Red worry there wasn’t enough. But a loud burp and a satisfied sigh reassured him that it was probably enough for now.

“thanks red. that was a good burg.” Zans said as he smiled up at Red, sockets still looking sad, but eyelights shining a little brighter. It made Red’s soul warm up a little.

“kmhm, ye. no problem.” Red cleared his throat and pressed out, one hand going to the back of his neck as he turned away. He could feel his cheeks warming up a bit, and hoped it wasn’t showing. He wasn’t that soft to blush over a fucking thanks.

“heh, you’re really the best red.” The little monster said as he snuggled into Red’s hand a bit more. Red could feel his cheeks warming up more and knew it was definitely showing now.

Fuck this was embarrassing.

“shut up an’ go ta sleep.” He growled, trying to mask the way his voice went up in pitch. He wasn’t gonna go all soft over his copy, no matter how small  and cute he looked!

Getting up he went to put Zans back down, still supporting his back as he reached for the blanket. But before he could pull his hand away, Zans’ hand snapped up and grabbed his sleeve, making him stop.

“stay? please?” Zans whispered out, voice weak and fragile, making Red strain to hear it.

He hesitated. It wouldn’t do anyone any good to get too attached when you didn’t know what horrors tomorrow would bring. But he could feel Zans’ hands tremble as he held onto his sleeve, tiny fists clenching the rough material. Red couldn’t take his sockets off them, seeing the desperation for company in that grip, feeling his soul slowly losing the fight.

“heh, sorry.” Zans said before Red could decide what to do. His hands lost their strength and he pulled them back, cupping his belly and looking down. Clearly giving up.

Red scowled. If he gave up that easily he would never survive in this hell hole. He would have to teach his alternate to toughen up or else.

Instead of saying anything Red grabbed Zans, making the smaller squeak in fright, and lifted him up. He quickly sat on the bed, making himself comfortable and putting the small skeleton between his legs, head cradled on his chest near his soul.

Zans looked up at him, sockets wide. Red just looked to the side, cheeks flushed and the ever-present scowl firmly in place. A few moments passed when the little monster’s face lit up, smile wide and tired sockets closed.

Without a word, he made himself comfortable, turning a little to the side so his belly wouldn’t press on his spine too much. When he was comfy, Zans cuddled his cheek into Red’s chest, enjoying the sound of Red’s soul frantically pounding behind his ribs. Red was trying to calm down and make it stop, but the more the little monster nuzzled into him, the harder it got. 

Red didn’t trust his own voice so he just let the other get comfortable, trying to do the same for himself by fluffing up the pillows under his spine. He was probably gonna be stuck here for a while so might as well make sure he can move his spine later.

He could feel Zans’ breathing slowly even out as his sockets sleepily closed. It wasn’t long until the little exhausted monster was completely asleep, breathing slow and relaxed. One of Zans’ hands wrapped around Red’s thumb, holding the hand close to his skull, the tips of Red’s claws touching his forehead. Red was still shocked how unafraid Zans was of him, but he didn’t complain.

He wasn’t tired enough to fall asleep yet and he couldn’t move. He should have fucking thought this trough better and taken them down to the couch instead so he could watch TV at least. But it was too late now, he wasn’t gonna risk waking the pregnant monster up.

Staring off into space, not thinking about much, he didn’t notice his free hand had started petting over Zans’ belly. He was pulled out of his thoughts by a soft rhythmic sound.

As he focused back on his lap he realized Zans had started purring softly. Red snapped his hand back when it hit him what he was doing, blushing hard and sockets wide. What the fuck was he doing?

Before he could freak out even more, a soft whine replaced the purring as Zans curled up more and shivered. Red looked down unsure what was wrong. The pitiful whine and weak shivering continued as Zans’ brows furrowed. He nuzzled harder into Red’s chest as if he was trying to get closer.

Reluctantly, Red lowered his hand back to the swollen belly, cowered in one of his thick red sweaters, and started rubbing it again. Slowly Zans stopped whining. The shivers slowed until he couldn’t feel them anymore and the tiny body uncurled, making it easier for Red to pet over the belly.

Red relaxed back into the pillows as the purring started up again. With a soft sigh, he focused down on the little monster. 

He knew he was in trouble. He was too _weak_ to keep his walls up for much longer. There was no way he would let anyone hurt this monster, not with everything he came to know about him, and not with how cute he was.

Red was truly fucked.

**Author's Note:**

> Thank you for reading! ♥＼(￣▽￣)／♥
> 
> I read The Letter Z while it was being posted and it's still one of my favourite fics X3
> 
> Since AssassinPyro13 opened the AU I couldn't resist putting Zans in a different setting at his most vulnerable, especially in a dangerous place like Underfell. But he was very lucky to end up with this Red. He is a mean one, no doubt about that, but he's secretly very weak to cute things and what's cutter then a tiny skeleton with babybones on the way >;3
> 
> Red basically went from "mercy murder" to "I've only had Zans for a day and a half, but if anything happened to him, I would kill everyone in this room and then myself" XD
> 
> But what does Zans think about the whole thing? Well... if there is enough interest I might write his POV so we can see ;3


End file.
